1. Field of the Invention
The present invention pertains to safety penetrating instruments and, more particularly, to safety needles having protected sharp tips to prevent inadvertent tissue contact.
2. Discussion of the Prior Art
Penetrating instruments are widely used in surgical procedures to gain access to anatomical cavities ranging in size from the abdomen to small blood vessels, such as veins and arteries, epidural, pleural and subarachnoid spaces, heart ventricles and spinal synovial cavities Such surgical penetrating instruments include a penetrating member or implement having a sharp tip or point to pierce or penetrate the tissue forming the cavity wall, and the force required to penetrate the cavity wall is dependent upon the type and thickness of the tissue of the wall. Once the wall is penetrated, it is desirable to protect the sharp tip of the penetrating member to prevent inadvertent contact with tissue in the cavity, and a particular problem exists where substantial force is required to penetrate the cavity wall in that, once penetration is achieved, the lack of tissue resistance can result in the sharp tip travelling too far into the cavity and injuring adjacent tissue.
Safety penetrating instruments including a safety probe biased to extend beyond the sharp tip of the penetrating member have become widely accepted for use in penetrating anatomical cavities. For example, the Verres needle, commonly used to create a pneumoperitoneum, has a spring-loaded inner member disposed within a tubular needle. U.S Pat. Nos. 1,527,291 to Zorraquin, No. 2,623,521 to Shaw and No. 2,630,803 to Baran are exemplary of safety penetrating instruments with a spring-loaded inner member disposed in a needle, while U.S. Pat. No. 4,254,762 to Yoon shows an endoscope spring-biased in a hollow needle. Safety trocars having a spring-biased protective shield disposed between an outer sleeve and an inner trocar are marketed by Ethicon, Inc. as the Endopath and by United States Surgical Corp. as the Surgiport. U.S. Pat. Nos. 4,535,773 to Yoon and No. 4,654,030 to Moll et al are exemplary of such safety trocars. German Offenlegungsschrift 2,544,262 discloses an intrauterine catheter including a tube having a distal sharp point, a spring-biased blunt member in the tube distal end and a hose or catheter slidable over the tube.
While prior art safety penetrating instruments are widely used, they suffer from many disadvantages when used in the procedures for which they are presently recommended; and, additionally, prior art safety penetrating instruments cannot be used in many procedures for which safety of penetration is highly desirable. One of the disadvantages of prior art safety penetrating instruments is that, when the penetrating member is a tubular needle with an acutely angled distal end, the sharp tip is not well protected and is still at least partially exposed when the safety probe is in the protective extended position.
Other disadvantages of prior art safety needles are that the safety probe cannot be controlled to provide selective locking or retraction of the safety probe.